Understanding Flash Sync Speeds

Flash Photography  •  Photography Tips

Confused about flash sync speeds? Wondering why you can’t sync to your flash at high shutter speeds? If you answered yes, it turns out you are not alone. The video below walks us through sync speeds, showing us what it’s all about:

Taylor starts his explanation with an old film camera, which he handily uses as a primer on shutter speeds. Once he’s sure everyone knows the basics of shutter speed, he moves on to the questions at hand. If the camera is capable of achieving shutter speeds upwards of 1/2000 of a second and the flash burst can fire at speeds of 1/4000 of a second, why can’t they sync up?

Taylor demonstrates how the shutters work on a camera.

Essentially, when shooting at higher shutter speeds the camera’s shutter curtains operate differently. Rather than opening all the way at one time. One of the shutters opens and begins closing soon after the second shutter starts to open, which means the light emitted from the flash cannot reach the entire scene. This results in dark lines across your image from the shutter curtains.

High speed sync, a feature on many cameras, takes care of the problem by pulsing the flash as the shutter curtains move so that the light can reach all parts of the photo. But it doesn’t come without compromises. To work properly, the flash power must be reduced.

A more expensive alternative is to use a camera that works differently. In the video, Karl Taylor demonstrates how a camera like the Hasselblad, which utilizes a leaf shutter system and allows the entire image to be exposed at the same time, making it (and other medium format cameras) capable of syncing at much higher shutter speeds.

“So, hopefully that little explanation gives you a simplistic overview of flash sync speeds and understanding why, even though you’ve got those super fast flash bursts, that you can’t fit those within shutter speeds that seem slower.”